U.S. ally Saudi Arabia is methodically harassing, detaining, and abusing human rights campaigners, going to “extreme lengths to hound critics into silent submission,” according to a report released Thursday by Amnesty International.

“The Saudi Arabian authorities have consolidated their iron grip on power through a systematic and ruthless campaign of persecution against peaceful activists in a bid to suppress any criticism of the state in the aftermath of the 2011 Arab uprisings,” said Said Boumedouha, Deputy Director of Amnesty International’s Middle East and North Africa Program.